What is an Optical Mouse Pad?

The optical mouse passes the LED light at the bottom, and the light hits the desktop at an angle of about 30 degrees, illuminating the shadow generated by the rough surface, and then feeding it back to the sensor through another lens through plane refraction. When the mouse moves, the imaging sensor records a continuous pattern, and then uses the "digital signal processor" (DSP) to analyze and process each picture before and after to determine the direction and displacement of the mouse, so that the mouse is on the screen. The coordinate values are transmitted to the Micro Controller Unit of the mouse via SPI. The processor of the mouse processes these values and sends them to the host computer.

Optical mouse

Right!

The optical mouse passes the LED light at the bottom, and the light hits the desktop at an angle of about 30 degrees, illuminating the shadow generated by the rough surface, and then feeding it back to the sensor through another lens through plane refraction. When the mouse moves,

Optical Mouse Mouse uses revolutionary optics

In 1963, the world's first mouse prototype was born in California, USA

Optical mouse with

CPI

In the process of using an optical mouse, you usually find the following problems: The mouse does not work properly on smooth surfaces such as glass and metal or some special colored surfaces, and the cursor is stuttered, trembling, drifting, or unresponsive, and even The cursor is missing. These two problems have not been completely solved until now. So why is this happening? The root cause is limited by the innate principle of the optical mouse, and we may wish to further analyze this.

We know that the optical engine of the optical mouse determines the position of the cursor by receiving the feedback image. If the moving surface is too smooth, it may not be able to produce enough diffuse reflection light. In this way, the intensity of the reflected light received by the sensor is very weak, making positioning The chip could not be identified, which caused the mouse to work abnormally. However, the current glass mouse pads and metal mouse pads on the market are not smooth, but are matte. The diffuse emission conditions are good, but there are still many optical mouse products that cannot work on them. This involves another reason. We know that the positioning chip judges the position information of the cursor by comparing the difference of feature points on adjacent image matrices, and the matte surfaces of some glass mouse pads and metal mouse pads are quite fine The surface is highly consistent. If it is a traditional optical-machine mouse, it can be described as moving and handy, but this is not the case for optical mice. The highly consistent surface causes the difference between different feature points to be too small. After the sensor converts them to digital signals, the difference cannot be reflected. Of course, the positioning chip is difficult to compare and process, which results in incomprehensible results for the mouse. Naturally, you should not expect it It works fine. However, sensor manufacturers can alleviate this problem by increasing the size of the CMOS sensor. The larger the size of the photoreceptor, the higher the resolution accuracy of the captured image. The larger the number of feature points, the more feature points can be compared by the positioning chip, so that a more accurate judgment can be made. Of course, the increase in the size of the sensor means that the amount of information to be processed is greater, and the computing capacity of the positioning chip must also be increased simultaneously. The current representative of this technical solution is Agilent s MX Optical Positioning Engine. The sensor specification of a common mouse is 22 × 22 pixels, and the MX Optical Positioning Engine is increased to 30 × 30 pixels. The volume has increased by 80%.

The answer to the problem of an optical mouse not working properly on some color surfaces (also known as "color blindness") is similar to the above. The optical engine achieves cursor positioning by capturing images and comparing differences, while capturing images requires the sensor to capture reflected light with a certain light intensity and uniform diffuse reflection. However, most sensors can only sense colored light at certain wavelengths, and cannot do anything with colored lights at other wavelengths. If the surface of the mouse pad can just absorb a large amount of colored light that can be sensed by the sensor, resulting in insufficient intensity of the reflected colored light and the sensor cannot effectively sense, it is naturally impossible to calculate the specific position of the cursor. However, "color blindness" is not a defect. Users only need to choose a mouse pad with a suitable color. If mouse manufacturers make every effort to solve this problem, I am afraid it will cost a lot.